Easy 5-Step Guide On How To Clean Composite Deck With Mildew

If you’re looking for a complete guide on how to clean composite deck with mildew, then you’re just in the right place. All you have to do is pre-rinse your deck before applying and rinsing off your preferred cleaning solution. 

Composite decks are designed to be durable and easy to care for, but that doesn’t mean it’s necessarily safe from mildew. Even though this type of fungus is much more manageable than mold, it will still look unsightly on your porch.

how to clean composite deck with mildew

Decks are the place where families can spend quality time outside the house. Homeowners like yourself must keep this area neat and clean. 

Keep reading to know the steps to clean your composite deck with mildew.


What Is Composite Decking?

Composite decking is a combination of synthetic and natural materials. It comes in a “plank form,” made from recycled wood and plastic scraps — making it a more eco-friendly option than wood decking. 

Did you know that composite decking can last for up to 25 to 30 years? Even more, if it’s well taken care of. 

This type of deck is a popular choice among homeowners because it offers a variety of earthy tones and colors to choose from. With that being said, here’s a post to help you choose composite decking colors.

Considering the amount of plastic in composite decking planks, you’d think that it’ll be safe from mold and mildew. However, if it’s not adequately protected and maintained, mildew can grow between the crevices and cling to the fine wood particles. 


How To Remove Mildew Off Of A Composite Deck


Step #1. Remove any furniture or potted plants

It would be wise to remove any furniture or plants off your deck before you start cleaning and scrubbing. Doing this will make it faster and easier to work on this project. 

Once you remove everything, you should first sweep the area from dust and loose debris. 

It can be a great time to check your deck for which areas are affected with mildew. These tips on what color is mildew will help you what exactly to look for. 

It will help if you mark these spots so you’ll have no trouble looking for them later on.


Step #2. Pre-rinse your composite deck

When you’re done sweeping the floor, the next thing you have to do is to pre-rinse your deck using a pressure washer or a garden hose. Doing this will prepare your deck for the next step. 

However, if you choose to use a pressure washer, be careful as the powerful streams of water can damage your deck. Make sure that you set it in the lowest setting and maintain an 8-inch distance from the floor before using it. 

Take a look at this post to know more about pressure washers


Step #3. Choose your cleaning solution

There are several cleaning solutions to choose from for this task, such as homemade ones like vinegar, baking soda, and hydrogen peroxide. Just combine it with water, and you have your DIY cleaning solution!

You may also use cleaning products specifically made for composite decks, which come in powder and liquid form. Carefully read the instruction label to know how to use it properly.

You may also use chemicals such as bleach. However, it can be quite dangerous to work with and destroy plants and vegetation around your deck. 


Step #4. Apply and scrub the affected areas

Once you’ve prepared your cleaning solution, apply it to the affected area. Then, get your soft-bristled brush and scrub the mildew off of your composite planks. 

You should ensure that every spot with mildew will get balanced concentration throughout this task. 

Leave your cleaning solution for a few minutes and let the cleaning agent do its magic. It will penetrate the mildew to remove it and stop it from growing any further in the future. 

For other tips, you may want to check out this article about how to remove mold from deck.


Step #5. Rinse thoroughly

The last step is to rinse your whole deck thoroughly. You may again use a pressure washer or a garden hose for this step. 

Doing this may seem simple enough, but we’re serious when we recommend rinsing everything carefully. Keep in mind that any residual layer of dirty water can trigger mildew and mold growth again on your deck in the future. 

After rinsing, it would help to allow 24 to 48 hours before you use your composite deck again. It is enough time for your whole deck to completely dry, depending on the weather. 



Learning how to clean composite deck with mildew is a valuable skill. However, we can’t deny that it can be pretty exhausting and laborious to do.

It would be best to rest the night before your project to ensure that you have all the energy you need. 

We also recommend you to do this project in nice and dry weather. Remember that you need one to two days’ worth of time to dry your deck before you can use it again.

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